CVE-2020-9817
📋 TL;DR
CVE-2020-9817 is a privilege escalation vulnerability in macOS that allows malicious applications to gain root privileges due to improper permission validation. This affects macOS systems running versions prior to Catalina 10.15.5. Attackers could exploit this to take complete control of affected systems.
💻 Affected Systems
- macOS
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with root-level access, allowing installation of persistent malware, data theft, and lateral movement across networks.
Likely Case
Local privilege escalation where a user with standard privileges could gain root access to install unauthorized software or modify system files.
If Mitigated
Limited impact if systems are fully patched, applications are from trusted sources only, and proper user privilege management is enforced.
🎯 Exploit Status
Requires user to execute a malicious application. No public exploit code was widely reported at disclosure time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Catalina 10.15.5
Vendor Advisory: https://support.apple.com/HT211170
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install macOS Catalina 10.15.5 update. 3. Restart the system when prompted.
🔧 Temporary Workarounds
Restrict application sources
allOnly allow applications from the App Store and identified developers
User privilege reduction
allOperate with standard user privileges instead of administrative accounts for daily tasks
🧯 If You Can't Patch
- Implement application whitelisting to prevent execution of unauthorized applications
- Use endpoint detection and response (EDR) tools to monitor for privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check macOS version: if running macOS Catalina earlier than 10.15.5, the system is vulnerable.Check Version:
sw_versVerify Fix Applied:
Verify macOS version is 10.15.5 or later and check that Security Update 2020-003 is installed.📡 Detection & Monitoring
Log Indicators:
- Unexpected privilege escalation events in system logs
- Processes running with unexpected root privileges
Network Indicators:
- Unusual outbound connections from system processes
SIEM Query:
process where parent_process_name contains 'sudo' or parent_process_name contains 'su' and user != 'root'